Dry Eye Syndrome(Dry Eyes, Keratoconjunctivitis Sicca)

Andrew A. Dahl, MD, FACS

Andrew A. Dahl, MD, is a board-certified ophthalmologist. Dr. Dahl's educational background includes a BA with Honors and Distinction from Wesleyan University, Middletown, CT, and an MD from Cornell University, where he was selected for Alpha Omega Alpha, the national medical honor society. He had an internal medical internship at the New York Hospital/Cornell Medical Center.

Charles Patrick Davis, MD, PhD

Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.

Dry eye syndrome facts

Dry eye syndrome is a very common and usually benign condition that is characterized by a disturbance of the tear film. This abnormality may result in disruption of the ocular surface, causing a variety of symptoms and signs and interference with quality of life.

To help keep the eyes comfortable and vision optimal, a normal, thin film of tears coats the eyes. Three main layers make up this tear film.

The innermost layer is the thinnest. It is a layer of mucin (or mucus). This very thin layer of mucus is produced by the cells in the conjunctiva (the clear skin that lines the eye). The mucus helps the overlying watery layer to spread evenly over the eye.

The middle (or aqueous) layer is the largest and the thickest. This layer is essentially a very dilute saltwater solution. The lacrimal glands under the upper lids and the accessory tear glands produce this watery layer. The function of this layer is to keep the eye moist and comfortable, as well as to help flush out any dust, debris, or foreign objects that may get into the eye. Defects of the aqueous layer are the most common cause of dry eye syndrome, also referred to as dry eye or keratoconjunctivitis sicca (KCS).

The most superficial layer is a very thin layer of lipids (fats or oils). These lipids are produced by the meibomian glands and the glands of Zeis (oil glands in the eyelids). The main function of this lipid layer is to help decrease evaporation of the watery layer beneath.

What is dry eye syndrome?

Dry eye syndrome (DES) -- also called dry eye or keratoconjunctivitis sicca (KCS) -- is a common disorder of the tear film that affects a significant percentage of the population, especially those older than 40 years of age. Dry eye syndrome can affect any race, and is more common in women than in men. Another term used for dry eye is ocular surface disease.

Dry Eyes and Contact Lenses

A properly fit contact lens should ride or float on the eye on a thin film of fluid (tear film). With each blink, this film of fluid between the contact lens and the eye is replaced with fresh fluid, allowing debris to be washed away and fresh oxygen that is dissolved in the fluid to reach the cornea. If this film is compromised in quantity or quality, the contact lens may become uncomfortable or even unhealthy to wear.

At each examination, the eye doctor will evaluate the fit of the contact lens and look for signs of early damage to the cornea that may be a result of a compromised tear film. If the contact lens itself is the problem, changing the lens curvature, diameter, or material may correct the problem. Sometimes the chemicals in multipurpose storage solutions for contact lenses can cause changes to the eye's surface that mimic chronic dry eye, and this can be eliminated by switching to a hydrogen-peroxide based cleansing system. Other causes of compromise include exposure to chronic wind and dust, and incomplete or infrequent blinking, such as when staring at a computer for long periods without resting the eyes.